Herring catch blamed for sluggish cod fishery

Tuesday

Jul 29, 2008 at 12:01 AMJul 29, 2008 at 4:11 PM

The catching of river herring has been prohibited in Massachusetts since 2006 and will remain so until next year. But Cape Cod Commercial Hook Fishermen’s Association believes the decline and the slow recovery of cod stocks could be linked to the harvest of sea herring by mid-water trawlers.

Rich Eldred

The catching of river herring has been prohibited in Massachusetts since 2006 and will remain so until next year. But Cape Cod Commercial Hook Fishermen’s Association believes the decline and the slow recovery of cod stocks could be linked to the harvest of sea herring by mid-water trawlers.

The herring fishery was the subject of Wellfleet Bay Wildlife Sanctuary’s summer lecture series last week.

“One hundred thousand metric tons are caught out at sea,” Lara Slifka, research program coordinator for the Hook Fishermen’s Association, told the audience. “Currently they are not overfished, but a lot of fishermen say those boats are catching too much herring. There is a concern that cod and tuna numbers are down, and that this is a possible cause.”

Sea herring eggs coat the sea floor – at depths of 50 to 150 feet – and are devoured as juveniles by flounder, cod, haddock and hake. A range of fish, mammals and birds eat the adults.

“We’ve determined the stock is not overfished and overfishing is not occurring,” Bill Overholtz, the head of the Pelagic Resource group at National Marine Fisheries Service in Woods Hole, said in a phone interview. “So that means the biomass is high and rate of removal is in an acceptable range.”

To be more precise, Overholtz said the estimated biomass of sea herring in the Gulf of Maine was 1 million metric tons, and last year’s harvest was 85,000 tons. A metric ton is 2,200 pounds. The Fisheries Service estimates the biomass is 65 percent above sustainable levels.

“Even though it’s the biggest fishery in New England, a relatively small component is removed, probably 5 percent to 10 percent of the stock,” Overholtz noted.

Some of the herring is canned in sardine form, some is frozen, a lot is used for bait and some is processed into fertilizer.

On Georges Bank the fishery began with foreign ships in 1961 and peaked in 1968 when 373,600 metric tons were taken. The harvest declined to 43,000 metric tons by 1976. Restrictions were put in.

“Starting in the mid-1980s they started to recover, and by the mid- to late-’90s both components (near shore and offshore) had fully recovered,” Overholtz said.

A new fisheries management plan was adopted in 1994, and mid-water trawling began on Georges Bank that year with a peak harvest of 35,000 metric tons in 2001.

“Mid-water trawling started in Ireland then moved to Alaska, and a lot of these boats are from Alaska,” Slifka said. “They’re mostly owned by American companies. There is a lot of money behind these boats. The commercial industry has a lot of power.”

After the collapse, the focus of the fishery shifted inshore and in 2001, 133,000 tons of herring were harvested in the Gulf of Maine, from Cape Cod to Nova Scotia.

“Historically the fishery has always been inshore,” Overholtz said. “Herring is a low-price, high-volume fishery, and it’s even more inshore now with the price of fuel. The catch out there (Georges Bank) has been low having to do with travel time, the price of fuel and the probability of finding fish. This is summer feeding season for herring, and they are spread out over a large area of Georges Bank. So it’s harder to find them.”

But it’s not so much the amount of sea herring caught by the trawlers that worries Slifka, it’s the bycatch of other fish, especially river herring.

“They (fishery officials) look at how much is landed. Not how much is caught and how much is discarded,” she said.

Sea herring are also caught in weirs, where unwanted bycatch can be tossed back over the nets, or in purse seines.

“Using purse seines and weirs, fish can be discarded alive. With trawlers they can’t,” Slifka said as she showcased a slide of dead hake floating beside a trawler.

River herring may be mixed in with the sea herring.

“Bluebacks and alewives are river herring,” Slifka explained. “They live in the ocean and migrate inshore to spawn. They (herring) all look similar. The only way to identify them is by touching the underside of the belly or by using a trained eye. River herring spend 80 percent of their lives offshore and they overlap when they’re out at sea. River herring are also being imperiled by this fishery.”

The herring travel together in large schools and can be swept up in the trawler’s nets.

“Midwater trawlers use nets that are 100 to 150 feet long, and are very non-selective,” Slifka said. “They basically catch everything in their path. Fish are being pumped on board at a rapid rate.”

There are observers on the boats to record the catch and bycatch, but Slifka said they are only on 1 percent to 5 percent of trawlers compared to 30 percent of smaller vessels.

“Right now we don’t have any complete record to say this is what they are catching,” she said. “Just as they are pumped onto the boat, they are pumped off into trucks and they don’t have a lot of people on shore watching. So we need to work on managing and knowing what is going on on these vessels.”

Skip King, who works as a media relations counsel for the Sustainable Fisheries Coalition, which represents much of the midwater trawler fleet, noted that budget cuts have slashed the number of observers.

“The MWT boats are required to notify regulatory bodies in advance of every trip and take an observer if one is sent,” he said in an e-mail. “They must call in prior to landing and notify authorities of the time and place of offload, so the fish can be observed at that time. So you know, several years ago as much as 20 percent of all trips were observed. That changed when federal observer funding was slashed – but the rates of bycatch haven't significantly changed.”

He also noted the nets have a larger mesh near the mouth, which is designed to let non-target fish, such as cod, escape. Herring, swimming in schools, tend to stay toward the center of the funnel but even many of them escape. Only the tail end of the net can hold fish.

Overholtz also said it is possible to distinguish river herring from sea herring, even as they fly past.

“It is hard for the general public,” Overholtz conceded. “But our observers are trained to recognize the differences between the different species of fish. There are certain field characters to look for. We just went on a cruise this month conducted by the National Marine Fisheries Service, aboard the research vessel Bigelow, and observed sea herring and river herring streaming by on a conveyor belt and we identified all of them.”

He doesn’t think the trawlers are capturing too many river herring.

“All indications are the bycatch of river herring by all gear types, and there are three of them, is relatively low,” Overholtz said. “A report will be coming out soon by the Atlantic States Marine Fisheries Council and they will try to estimate what the take of river herring is.”

“Bycatch happens on a regular basis,” King agreed. “I don’t care whether it’s commercial or recreational but as a percentage of the catch, it’s really small. There is pretty extensive data that shows that.”

Slifka wants more observers and scales at the docks.

“We are working with the federal government to get better observer coverage,” she said.

A new herring management plan is being drawn up and Overholtz said it would factor in the role of herring as food for cod and other species.

“It’s not right on the cusp of our approach but it’s in there,” he promised. “A number of issues will be addressed one way or another.”